This invention relates to the art of roll grooving apparatus and, more particularly, to improvements in such apparatus relating to the quick release of grooving roll components and maintaining tracking between the grooving rolls and workpiece so that the rolled groove is transverse to the workpiece axis.
The present invention finds particular utility in conjunction with a portable roll groover which is adapted to be interengaged with a rigidly supported pipe to be grooved and which, during the roll grooving operation, travels about the periphery of the pipe. Accordingly, the invention will be illustrated and described herein in conjunction with such a portable roll groover; however, it will be understood and appreciated from the disclosure herein that the invention is applicable to roll grooving apparatus of the character wherein the roll groover is rigidly supported and the pipe to be grooved rotates relative thereto during the grooving operation.
Roll grooving apparatus is of course well known and, generally, includes relatively displaceable first and second housing components or supports respectively rotatably supporting a backup grooving roll and an idler grooving roll between which a pipe to be grooved is interposed during a grooving operation. The grooving rolls are matingly contoured and, in this respect, the backup roll is provided with a peripheral groove and the idler roll is provided with a peripheral projection such that a pipe therebetween is provided with a peripheral groove upon relative rotation of the grooving rolls and relative radial displacement of the grooving rolls toward one another. Most often, the backup roll is a drive roll rotated by a hand tool or by a drive motor depending on the particular type of roll grooving apparatus, but both the backup and idler rolls can idle in apparatus of the type wherein the pipe is rotated during the roll grooving operation.
Often, relative displacement between the grooving roll supports is achieved through the use of threaded feed screw arrangements between the supports and which include a screw component which is manually rotated by hand or by a tool such as a wrench. The grooving roll supports are interengaged for linear or pivotal displacement toward and away from one another, whereby it will be appreciated that considerable time is required to set up and to perform a roll grooving operation on a pipe. In this respect, the feed screw must be manually rotated in the direction to separate the grooving rolls to facilitate the insertion of the end of a tube therebetween, and the feed screw must then be manually rotated in the opposite direction to bring the backup and idler grooving rolls into engagement with the pipe. The workpiece, backup roll and idler grooving roll are then relatively rotated, and the feed screw is manually rotated in the direction to displace the idler grooving roll toward the backup roll to progressively form the peripheral groove in the pipe. When the desired groove depth is reached, relative rotation is stopped and the feed screw is manually rotated in the opposite direction until there is sufficient clearance between the two rolls to accommodate removal of the grooved pipe from between the rolls.
In addition to the time required to manually rotate the feed screw for displacing the grooving rolls away from one another upon completion of a roll grooving operation, it has been impossible heretofore to quickly release the grooving rolls so as to preclude damage to the latter and/or damage to the pipe, or the imposition of undesirable forces on the rolls and other component parts of the roll grooving apparatus upon the occurrence of a problem during the roll grooving operation. For example, it is necessary for the pipe and grooving roll axes to be properly aligned during a roll grooving operation so that the track of the groove is transverse to the pipe axis. Misalignment at the beginning of the operation can cause the track of the groove to be spiral relative to the pipe axis causing the pipe and/or grooving rolls to "walk" in the direction to axially separate the rolls and pipe. If the idler grooving roll is not displaced from the pipe immediately, the pipe can be damaged to the extent that the grooving operation can not be completed so as to provide an acceptable end product. Moreover, axial separation of the pipe and roll grooving apparatus can subject the operator to injury and/or the pipe or grooving apparatus to damage. If the roll grooving apparatus is motor driven, the undesirable tracking can not be quickly stopped in that displacement of the idler grooving roll from engagement with the pipe requires manual rotation of the threaded feed screw. Even if the roll grooving apparatus is manually driven about the periphery of the pipe, improper tracking requires manual displacement of the idler roll through rotation of the feed screw in order to reset the grooving apparatus relative to the pipe.
The tracking problem referred to above is attendant to the operation of any roll grooving apparatus including those in which the grooving roll supports are relatively displaced other than by a feed screw and, for example, hydraulically as shown in U.S. Pat. No. 3,995,466 to Kunsmann, and manually through a pivotal lever arm as disclosed in U.S. Pat. No. 5,079,940 to Pulver et al. Numerous efforts have been made heretofore to provide roll grooving apparatus with a self tracking feature, and these efforts have included supporting the pipe to be roll grooved at an incline to the axes of the grooving rolls as disclosed in the aforementioned patent to Kunsmann, and by inclining the axis of the idler grooving roll relative to the axis of the backup roll as disclosed in U.S. Pat. No. 4,041,747 to Elkin. Other efforts have included contouring the outer surface of the backup roll in the form of a frustum of a cone as disclosed in U.S. Pat. No. 5,279,143 to Dole, and by providing an auxiliary roller engaging the outer surface of a pipe being grooved and having its axis slanted relative to that of the pipe as disclosed in U.S. Pat. No. 2,975,819 to Costanzo et al. While all of the foregoing arrangements promote self tracking, they add undesirably to the expense of the roll grooving apparatus by requiring additional and/or specially designed component parts for the apparatus, thus adding to the cost of maintaining the apparatus as well as the cost of manufacturing the same.